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  • 1
    Electronic Resource
    Electronic Resource
    The pineal gland of nocturnal mammals (1981)
    Springer
    Cell & tissue research 216 (1981), S. 253-271 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Cell populations ; Bat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the pineal gland of the pipistrelle bat two different populations of pinealocytes and glial cells were observed electron microscopically. The pinealocytes of populations I and II differ in their content of metabolically active cell organelles. In the pinealocytes of population I, granular vesicles originating from the Golgi apparatus were found in the perikaryon and especially in the endings of the pinealocyte processes. Granular vesicles appeared to be more numerous in hibernating nulliparous females. The pinealocytes of population II are characterized by the presence of small cytoplasmic vacuoles, probably originating from cisternae of the granular endoplasmic reticulum and containing flocculent material of moderate electron density. The classification of the pinealocytes belonging to population II is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233619
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of a short light pulse at night on the ultrastructure of the rat pinealocyte: a quantitative study (1988)
    Springer
    Cell & tissue research 254 (1988), S. 247-249 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocyte ; Light exposure ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Although it is generally known that light strongly influences N-acetyltransferase activity and melatonin production in the pineal gland, little information is available concerning morphological changes following light exposure. As exposure of rats to a short light pulse at night rapidly depresses melatonin synthesis, we decided to determine whether this experimental condition produces rapid changes in the pinealocyte organelles. A 30-min light pulse at night (six hours after lights out) provoked rapid changes in the relative volumes of some pinealocyte organelles. The volume fractions of mitochondria, Golgi apparatus and lipid droplets, and the numbers of dense-core vesicles and “synaptic” ribbons decreased, whereas the volume fraction of lysosomes increased. There were no differences in the volumes of granular endoplasmic reticulum and vacuoles containing flocculent material in those animals exposed to light compared with control animals. These results indicate that a short light pulse at night causes ultrastructural changes that can be interpreted as morphological features of diminished activity of pinealocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220041
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The pineal gland of equatorial mammals (1980)
    Springer
    Cell & tissue research 210 (1980), S. 417-433 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Ultrastructure ; Malaysian rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les pinéalocytes d'un Rat de Malaisie (Rattus sabanus), un animal vivant près de l'équateur donc dans une zone où les variations annuelles de la longueur des jours sont minimes, examinés au microscope électronique ont été comparés à ceux d'autres Mammifères. Une seule population de pinéalocytes a été observée. La présence d'un grand nombre de vésicules granulaires et de rubans circonscrits par des vésicules est la caractéristique premi`ere des pinéalocytes de cette espèce. Les rubans circonscrits par des vésicules ont été plus spécialement observés dans les terminaisons des prolongements des pinéalocytes où ils sont nombreux et la plus souvent en contact directe avec l'espace périvasculaire. L'importance physiologique de ces rubans circonscrits par des vésicules et des vésicules granulaires est discuté.
    Notes: Summary The ultrastructure of the pinealocytes of the Malaysian rat (Rattus sabanus), a mammal inhabiting a zone near the equator where the annual variations of daylength are inconspicuous, was examined and compared with that of pinealocytes of other mammals. On the basis of the presence of granular vesicles, only one population of pinealocytes was found. A large number of granular vesicles and vesicle-crowned rodlets is characteristic of the pinealocytes of this equatorial species. Vesicle-crowned rodlets are especially numerous in the endings of the pinealocyte processes and; they most often found in direct topographical connection with the perivascular spaces. The physiological significance of the presence of such large amounts of vesicle-crowned rodlets and of the secretory process characterized by the formation of granular vesicles is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220199
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The pineal gland of the mole (Talpa europaea L.) (1980)
    Springer
    Cell & tissue research 206 (1980), S. 417-430 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocyte ; Fetus ; Mole ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the pinealocytes in the fetal mole (Talpa europaea) was examined and compared with that in the adult mole. The parenchyma of the fetal pineal gland consists primarily of pinealocytes with very few dispersed “glial” cells. Three different morphological types of pinealocytes (I, II and III) were observed. Pinealocytes of types I and II, homologous to the rudimentary photoreceptor cells of lacertilians and birds, were commonly found, especially around the pineal lumen, which is still present in the fetus. These results support the concept of the phylogenetic origin of mammalian pinealocytes from the pineal photoreceptor cells of the non-mammalian vertebrates. Considering their synthetic/secretory activity, the pinealocytes of the mole fetus are characterized by the presence of accumulations of proteinaceous material (APM) in the cisternae of the granular endoplasmic reticulum (GER). Two types of APM were also found. One type shows a paracrystalline organization as described in the adult mole. In the fetus, however, the paracrystalline-organized APM occur only infrequently. A progressive transformation, via an increase in size or fusion of vacuoles containing material originating from the cisternae of the GER in APM, free of a paracrystalline structure, has been observed. Granular vesicles (GV) originating from the Golgi saccules were rarely observed. Sometimes GV and APM were found to be present in the same cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237971
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The ultrastructure of pinealocytes in the golden mole (Amblysomus hottentotus) with special reference to the granular vesicles (1978)
    Springer
    Cell & tissue research 191 (1978), S. 39-56 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Golden mole ; Secretory process ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les pinéalocytes de la glande pinéale de la Taupe dorée Amblysomus hottentotus (Mammifère aveugle et vivant toujours dans une obscurité complète) examinés au microscope électronique ont été comparés à ceux d'autres Mammifères. Une seule population de pinealocytes a été observée. Mitochondries, ribosomes, réticulum endoplasmic granulaire, inclusions lipidiques et rares structures lysosomiales sont présents dans le périkaryon. De nombreux grains de glycogène formant le plus souvent de typiques “accumulations” ont été fréquemment observés associés à des vacuoles. Un grand nombre de vésicules granulaires est la caractéristique première des pinéalocytes. Un phénomène d'excrétion, caractérisé par une dissolution in situ du coeur dense, a été observé. L'importance physiologique de ces vésicules granulaires est discuté.
    Notes: Summary The ultrastructure of the pinealocytes of the golden mole (Amblysomus hottentotus), a blind subterranean mammal living in complete darkness, was examined and compared with that of pinealocytes of other mammals. On the basis of the presence of granular vesicles and glycogen granules, only one population of pinealocytes was found. Large mitochondria, ribosomes, lipid inclusions and scarce lysosomes were observed in the perikaryon. Numerous glycogen granules, often forming typical accumulations, were frequently found to be associated with typical vacuoles. An extraordinary large number of granular vesicles is characteristic of the golden mole pinealocyte. Phenomena of excretion of compound(s) stored in the granular vesicles were identified. Morphologically this is characterized by dissociation of its granular core in situ while its limiting membrane is preserved. The physiological significance of the secretory process characterized by the formation of these granular vesicles is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223214
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    Paper (German National Licenses)
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